PIN FUNCTION DESCRIPTION
Power input to the chip.
2 2 +12V Input for overvoltage and undervoltage for the +12V rail.
3 3 +5V Input for overvoltage and undervoltage for the +5V rail.
4 4 + 3.3V Input for overvoltage and undervoltage for the +3.3V rail.
5 -5V Input for overvoltage and undervoltage for the -5V rail .
Input for overvoltage and undervoltage for the -12V rail.
This function may disabled by tying this pin to a positive
voltage above 2.4V.
Signal ground and silicon substrate
8 7 HYST Open collector output of the AC undervoltage
comparator. A resistor between this pin and AC will
provide hysteresis to the AC undervoltage sensing.
Pulling this pin low will reset the FAULT latch and
discharge the start-up timing capacitors, UVB and PG
CAP, allowing normal start-up of the system. Pulling this
pin high will send the FAULT signal high, prompting a
AC Non-inverting input to the AC undervoltage sensing
comparator. If the AC pin is less than 2.5V, POK goes low
and UVB cap discharges.
11 10 PG CAP A cap to ground provides a delay between undervoltage
sensing becoming good and the POK output going high.
Cap discharges whenever an output or AC undervoltage
Open collector output of the undervoltage sensing
comparators. This pin goes low upon an undervoltage
condition. Except for the delay set by the PG CAP, this
pin always reflects the actual state of the undervoltage
13 12 DELAY A cap to ground will delay the FAULT signal when the
OFF pin is used to shut down the system. The POK will
signal a power fail warning immediately, but the FAULT
shutdown of the power supply will be delayed.
A cap to ground provides start-up blanking of the
undervoltage sensing portion of the FAULT signal. This
pin may also be grounded to prevent undervoltage
conditions from triggering the Fault signal. This pin
discharges the cap whenever AC goes low or the FAULT
pin goes high.
15 14 VREF 2.5 V Voltage reference. This is a series regulator type
16 15 FAULT Open collector output of the overvoltage and
Crow bar drive output of the overvoltage faults only.